U-shaped fluorescent lamp with improved envelope-bracing means

ABSTRACT

The leg portions of a U-shaped fluorescent lamp are joined together and reinforced by a rigid wire harness that extends into and is interlocked with the base members secured to the ends of the envelope. The harness passes through openings in the base collars and has arcuate end segments that are seated within the base cavities and are held in such position by the base collars and the basing cement. Flexing of the envelope legs and the potential risk of lamp breakage during handling and installation of the lamp in its fixture are thus eliminated.

United States Patent Inventor Appl. No.

Filed Patented Assignee U-SHAPED FLUORESCENT LAMP WITH IMPROVED ENVELOPE-BRACING MEANS 6 Claims, 6 Drawing Figs.

11.8. I 313/109, 240/5l.12, 313/220, 313/318 Int. l-l05b 33/02 Field ofSearch 313/109, 220, 318; 240/51.12

[56] References Cited UNITED STATES PATENTS 3,337,035 8/1967 Pennybacker 240/5 1. l2 FOREIGN PATENTS 933,526 9/1955 Germany 240/5 [.12

Primary ExaminerWilliam L. Sikes Attorneys-A. T. Stratton, W. D. Palmer and D. S. Buleza ABSTRACT: The leg portions of a U-shaped fluorescent lamp are joined together and reinforced by a rigid wire harness that extends into and is interlocked with the base members secured PATENTEU M1831 l97| SHEET 1 BF 2 FIG.

AGENT Z Y U-SIIAPED FLUORESCENT LAMP WITH IMPROVED ENVELOPE-BRACIN G MEANS CROSS-REFERENCES TO RELATED APPLICATIONS None BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electric lamps and has particular reference to an improved U-shaped fluorescent lamp.

2. Description of the Prior Art Fluorescent lamps having U-shaped envelopes are well known in the art and are becoming quite popular in the industry since they provide compact high-intensity light sources and thus reduce the size of the lighting fixtures. However, marketing tests have shown that the legs of such lamps have a tendency to flex, particularly when the lamp is being installed into its fixture. There is, accordingly, a potential danger that such flexing may cause the envelope to break and injure personnel handling the lamp. Maintaining the base pin-to-base pin spacing of the finished lamp within established tolerances is also difficult due to many variables that influence the envelopebending operation and the relative position of the envelope legs.

In order to eliminate such potential hazards and quality control problems, it has become the common practice to reinforce the free ends of such lamps and prevent them from being compressed or spread apart. A slip-on brace member designed with these objectives in mind in disclosed in US. Pat. No. 3,337,035 issued Aug. 22, 1967 to M. Pennybacker. The brace is made from stiff wire and is provided with arcuate loops at each end that are slipped over and compressively grip the legs of the U-shaped envelope. While braces of this type achieve the desired purpose, they are not entirely satisfactory since variations in the dimensions of the envelope and looped portions of the brace may cause the brace to fit too tightly or too loosely on the lamp. If it fits too loosely the brace may shift position on the lamp and allow the pin-to-pin spacing to change. In addition, since the brace is of a predetermined length, lamps having envelope legs that deviate from the nominal leg-to-leg spacing have to be compressed or spread apart before the lamp will accommodate the brace and permit the latter to be slipped onto the lamp. This, obviously, is undesirable since it strains the bent portion of the glass envelope.

Braces which are formed to interfit with metal shells of specially designed base members are also known in the art but are also not entirely satisfactory since they will not accommodate lamps having legs that deviate from the normal leg-to-leg spacing. Such lamps thus also have to be distorted to fit the brace. Alternatively, a series of braces of different lengths must be stocked and each brace custom-fitted with each lamp during assembly.

SUMMARY OF THE INVENTION The aforesaid problems and disadvantages are eliminated in accordance with the present invention by utilizing a harness that is made from stifl' wire and is terminated at each end by a bent segment that is shaped and dimensioned to fit within the cavity of a conventional fluorescent lamp base between the end wall of the base and the sealed end of the glass envelope. The harness extends through aligned openings in the collar portions of the respective bases and the bent end segments are securely locked within the base cavities by the cement which joins the bases to the sealed ends of the envelope.

The end segments of the harness are preferably of arcuate configuration and are made slightly smaller than the inside dimensions of the cylindrical base collars so that there is a sufficient amount of play between the harness and the respective bases to compensate for variations in the leg-to-leg spacing of the envelope. The hamess-base assembly can thus be fitted onto and cemented to the sealed-in lamp without distorting the envelope in any way. Once the basing cement is cured, the harness is rigidly joined to the base structures and remains in fixed position on the lamp.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readily apparent from the following exemplary description in connection with the accompanying drawings, wherein:

FIG. 1 is an elevational view of a U-shaped fluorescent lamp embodying the improved reinforcing harness and structure of the present invention;

FIG. 2 is an enlarged perspective view of the wire harness used in the lamp shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the based ends of the lamp shown in FIG. 1 illustrating the manner in which the arcuate ends of the harness are interlocked with the respective bases;

FIG. 4 is a cross-sectional view through the based ends of the lamp along the line IV-IV of FIG. 3;

FIG. 5 is an enlarged perspective view of an alternative form of wire harness; and

FIG. 6 is an elevational view of the based ends of a U- shaped fluorescent lamp that is provided with the harness depicted in FIG. 5, the base members being shown in cross section to illustrate the interlocked juncture of the harness and the respective bases.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is shown a U-shaped fluorescent lamp 10 which embodies the preferred form of the present invention and consists of a tubular vitreous envelope 11 that is bent to form a pair of spaced leg portions 12 and 13 of the same length. The envelope leg 12 is hermetically sealed by a conventional tubulated mount comprising a glass stem 14 and a pair of lead wires 16 that are sealed through the stem and sup port a cathode 18. The other envelope leg 13 is sealed by a nontubulated mount consisting of a glass stem 15, lead wires 17 and a cathode 19.

As shown more particularly in FIG. 3, plastic base members 20 and 21 are fastened to the sealed ends of the envelope legs 12 and 13 by rings of cured basing cement C and the outer ends of the lead wires 16 and 17 are connected to two pairs of spaced contact pins 22 and 23 anchored in the end walls of the respective bases. The inner surface of the envelope 11 is coated with a layer P of suitable ultraviolet-responsive phosphor and the envelope is evacuated and charged with a measured amount of mercury and a suitable fill gas such as a mixture of neon and argon at a pressure of a few millimeters of mercury in the usual fashion. The cathode 18 and 19 are conventional and consist of tungsten wire coils that are coated with a suitable electron-emissive material.

The base members 20,21 need not be made of plastic and well-known metal bases with insulated pin inserts can be used.

Flexing and possible breakage of the U-bent envelope 11 is prevented in accordance with this embodiment of the invention by means of a rigid elongated bracing member such as a harness 24 of stiff wire that is mechanically interlocked with the base members 20 and 21 and securely holds the leg portions 12 and 13 of the envelope 11 and contactpins 22,23 in the desired spaced-apart relationship.

As will be noted, in FIG. 2, the harness 24 has a substantially straight medial section 25 that is terminated by curved end segments 26 and 27 of semicircular configuration that are disposed in a common plane and have a predetermined center-to-center dimension :c".

As shown in FIGS. 3 and 4, the semicircular end segments 26 and 27 of the harness 24 are located within the cavities formed by the end walls and the cylindrical sidewalls or collars of the-respective base members 20 and 21 and are sandwiched between the end walls of the bases and the sealed ends of the envelope 11. The curvature and dimensionsof these semicircular segments 26,27 are such that they are slightly smaller than the inner diameter of the cylindrical collars of the respective bases 20,21.

In the case of an envelope 11 having a nominal leg-to-leg spacing, the arcuate ends 26,27 of the harness 24 will thus be spaced inwardly a small distance from the base collars, as shown. The portions of the straight medial section 25 of the harness 24 immediately adjacent the curved ends 26 and 27 extend through apertures 28 and 29 in the collar portions of the bases and 21, respectively. These apertures are aligned with one another and are so located that the medial portion of the harness 24 is in line with the two sets of base pins 22 and 23 (as shown in FIG. 4). The curved end segments 26 and 27 span diametrically-opposed portions of the base collars, as will be noted in FIGS. 3 and 4 and are thus restrained by the base collars and prevented from inadvertently contacting the leads 16,17 and the staked inner ends of the base pins 22,23.

The medial segment 25 of the harness 24 does not have to be straight-it can be shaped as desired as long as it is of the proper length to provide the required pin-to-pin spacingflt can also comprise a metal stamping rather than a preformed wire member.

While the harness 24 is mechanically interlocked with the base members 20 and 21 by virtue of the interfitting of the semicircular end segments 26 and 27 with the associated base collars, a stronger and more rigid juncture can be provided by placing the arcuate end segments 26,27 of the harness 24 in contact with the basing cement C that extends around the inner peripheries of the base collars so that the cement, when subsequently cured and hardened, bonds the harness to the respective bases and provides an integral structure. This construction is shown in FIG. 3 and is preferred since it provides an arrangement wherein the harness 24 is rigidly joined to the respective base members 20 and 21 by the overlying rings of basing cement C.

Assembly of the wire harness 24 with the bases 20 and 21 is readily accomplished by depositing the rings of cement C into the base collars to the proper depth, slipping the arcuate ends of the harness into the bases through the sidewall apertures 28 and 29 to form a base-harness assembly, and then placing the bases on the respective sealed ends of the envelope 11 and curing the cement C in the usual manner by heating.

SPECIFIC EXAMPLE As a specific example, satisfactory results have been obtained in the case of a 40-watt T12 fluorescent lamp having a U-shaped envelope with a nominal leg-to-leg spacing (centerto-cent'er) of l52.4 mm. by using conventional phenolic plastic bases having an inner collar diameter of approximately 34 mm. and a wire harness fabricated from stainless steel wire that had a diameter of 1.27 mm., an overall length of approximately 185 mm., and semicircular end segments that had radii of 15.5 mm. and were spaced 152.4 mm. apart (center to center dimension 1" in FIG. 2). The holes 28 and 29 in the base collars had a diameter of approximately 2.5 mm. and their lower edges were substantially flush with the inner surface of the end walls of the bases.

ALTERNATIVE EMBODIMENT In FIGS. 5 and 6 there is shown an alternative embodiment wherein the brace consists of a rigid wire harness 30 having a straight medial section 31 that is terminated by circular segments 32 and 33 which are disposed in a common plane and are slightly smaller than the base collars. Since the base engaging portions of the harness 30 are circular in configuration, they cannot be assembled with the base members 20a and 21a (FIG. 6) by inserting the ends of the harness through apertures in the prefilled bases as in the embodiment above described.

Hence, as will be noted in FIG. 6, each of the base members 20a and 21a are provided with slots 34 and 35, respectively, that are aligned with one another and extend from the peripheries of the base collars toward the ends of the bases a sufficient distance to accommodate the straight section 31 of the harness 30 immediately adjacent thecircular ends 32,33.

The ends 32 and 33 are thus simply slipped into the slotted bares 20a and 21a and rings of basing cement C are deposited around the inner periphery of the base collars and over the adjacent surfaces of the circular ends 32 and 33, thus forming a hamess-base assembly that is placed onto the sealed ends of the envelope leg portions 12a and 13a. The cement is then cured by heat to provide a U-shaped fluorescent lamp 10a that has envelope leg portions 12a and which are securely joined together by a wire harness 30 that is bonded to and thus constitutes an integral part of the base structures as in the case of the preferred embodiment described previously.

It will be appreciated from the foregoing that a very simple :and economical means has been provided for reinforcing the ilegs of a U-shaped fluorescent lamp and preventing the enivelope from being inadvertently distorted and broken during ;the lamp assembly operations and subsequent handling of the finished lamp during shipment and placement in its fixture. The bracing structure is such that it permits the use of conventional type bases, automatically compensates for variations in the leg-spacing dimensions of the bent envelopes and becomes an integral part of the base structures during the normal sequence of lampmaking operations.

I claim as my invention:

1. In combination with a fluorescent lamp having a U- shaped vitreous envelope, means for reinforcing and locking the leg portions of said envelope in predetermined spacedapart relationship comprising;

a pair of hollow base members secured to the respective ends of said envelope leg portions and having side and end walls which define a base cavity at each end of the lamp, and

a rigid elongated member joining said envelope leg portions and having end segments that extend through openings in the walls of the respective base members into said base cavities and are in interlocked relationship with the interior surfaces of said base members.

2. The U-shaped fluorescent lamp of claim 1 wherein;

each of said base members are fastened to the respective ends of said envelope leg portions by a body of cured cement, and

portions of the interlocked end segments of said rigid elongated member are joined to the respective base members by the associated body of cured cement.

3. The U-shaped fluorescent lamp of claim 2 wherein;

the ends of said envelope leg portions are of substantially circular cross section,

the sidewalls of each of said base members comprise a cylindrical collar that encircles the adjoined end of the associated envelope leg portion,

said body of cured cement extends around the inner periphery of the respective base collars, and

said rigid elongated member comprises a wire harness having arcuate end segments that span diametrically-opposed parts of the respective base collars and are joined to said collars by said cement.

4. The U-shaped fluorescent lamp of claim 3 wherein the maximum width dimensions of said arcuate end segments are smaller than the inside diameter of the respective base collars and parts of said end segments are spaced inwardly from the collars.

5. The U-shaped fluorescent lamp of claim 4 wherein;

said wire harness has a substantially straight medial segment and semicircular end segments that are disposed in a common plane, and

said wire harness extends through substantially aligned apertures in the collars of the respective base members.

6. The U-shaped fluorescent lamp of claim 4 wherein;

said wire harness has a substantially straight medial segment and circular end segments that are disposed in a common plane, and

said wire harness extends through substantially aligned slots in the collars of the respective base members that extend MT from the collar peripheries toward the end walls of said base members. 

1. In combination with a fluorescent lamp having a U-shaped vitreous envelope, means for reinforcing and locking the leg portions of said envelope in predetermined spaced-apart relationship comprising; a pair of hollow base members secured to the respective ends of said envelope leg portions and having side and end walls which define a base cavity at each end of the lamp, and a rigid elongated member joining said envelope leg portions and having end segments that extend through openings in the walls of the respective base members into said base cavities and are in interlocked relationship with the interior surfaces of said base members.
 2. The U-shaped fluorescent lamp of claim 1 wherein; each of said base members are fastened to the respective ends of said envelope leg portions by a body of cured cement, and portions of the interlocked end segments of said rigid elongated member are joined to the respective base members by the associated body of cured cement.
 3. The U-shaped fluorescent lamp of claim 2 wherein; the ends of said envelope leg portions are of substantially circular cross section, the sidewalls of each of said base members comprise a cylindrical collar that encircles the adjoined end of the associated envelope leg portion, said body of cured cement extends around the inner periphery of the respective base collars, and said rigid elongated member comprises a wire harness having arcuate end segments that span diametrically-opposed parts of the respective base collars and are joined to said collars by said cement.
 4. The U-shaped fluorescent lamp of claim 3 wherein the maximum width dimensions of said arcuate enD segments are smaller than the inside diameter of the respective base collars and parts of said end segments are spaced inwardly from the collars.
 5. The U-shaped fluorescent lamp of claim 4 wherein; said wire harness has a substantially straight medial segment and semicircular end segments that are disposed in a common plane, and said wire harness extends through substantially aligned apertures in the collars of the respective base members.
 6. The U-shaped fluorescent lamp of claim 4 wherein; said wire harness has a substantially straight medial segment and circular end segments that are disposed in a common plane, and said wire harness extends through substantially aligned slots in the collars of the respective base members that extend from the collar peripheries toward the end walls of said base members. 